ENDOCRINOLOGY

Sadly, Diabetes Mellitus is one of the most common endocrine disorders we diagnose here at Fountain City Animal Hospital.  We’ve seen a tremendous increase in the number of cats we’ve diagnosed with the condition over the years, but the occurrence in dogs also seems to be escalating.  Simply put, diabetes occurs when the pancreas doesn't produce enough insulin, the hormone required for the body to efficiently use sugars, fats and proteins.

Diabetes most commonly occurs in middle aged to older dogs and cats, but occasionally occurs in young animals. When diabetes occurs in young animals, it is often genetic and may occur in related animals. Diabetes mellitus occurs more commonly in female dogs and in male cats. 

Certain conditions predispose a dog or cat to developing diabetes. Most importantly, animals that are overweight or those with inflammation of the pancreas are predisposed to developing diabetes.  This is part of the reason all the staff at Fountain City Animal Hospital shows such unrelenting attention to your pet’s body weight.  Some drugs can interfere with insulin, leading to diabetes. Glucocorticoids, which are cortisone-type drugs are the most often incriminated in the development of diabetes.  They are fairly commonly used drugs, and luckily only a small percentage of animals receiving these drugs develop diabetes.

The body needs insulin to use sugar, fat and protein from the diet for energy.  Without insulin, sugar accumulates in the blood and spills into the urine.  Sugar in the urine causes the pet to pass large amounts of urine and to drink lots of water.  Levels of sugar in the brain control appetite.  Without insulin, the brain becomes sugar deprived and the animal is constantly hungry, yet they may lose weight due to improper use of nutrients from the diet. Untreated diabetic pets are more likely to develop infections and commonly get bladder, kidney, or skin infections. Diabetic dogs, and rarely cats, can develop cataracts in the eyes. Cataracts are caused by the accumulation of water in the lens and can lead to blindness. Fat accumulates in the liver of animals with diabetes. Less common signs of diabetes are weakness or abnormal gait due to nerve or muscle dysfunction.  There are two major forms of diabetes in the dog and cat: 1) uncomplicated diabetes and 2) diabetes with ketoacidosis. Pets with uncomplicated diabetes may have the signs just described but are not extremely ill.  Diabetic pets with ketoacidosis are usually very ill and may be vomiting and depressed.

The diagnosis of diabetes is made by finding a large increase in blood sugar and a large amount of sugar in the urine.  Animals, especially cats, stressed by having a blood sample drawn, can have a temporary increase in blood sugar, but there is no sugar in the urine.  A blood screen of other organs is obtained to look for changes in the liver, kidney and pancreas.  A urine sample may be cultured to look for infection of the kidneys or bladder. Diabetic patients with ketoacidosis may have an elevation of waste products that are normally removed by the kidneys.

The treatment is different for patients with uncomplicated diabetes and those with ketoacidosis.  Ketoacidotic diabetics must be hospitalized to be treated with intravenous fluids and rapid acting insulin.  This treatment is continued until the pet is no longer vomiting and is eating, and then the treatment is the same as for uncomplicated diabetes.

Diabetes mellitus is a treatable condition. Although long-term treatment requires commitment and dedication, it can be rewarding to manage this condition successfully in a beloved pet.

Initial steps in treating a diabetic pet may involve removal of any predisposing causes for the diabetes. For example, the withdrawal of cortisone-like drugs may lead to resolution of the condition. Since obese cats are more prone to develop diabetes, weight reduction can lead to resolution of the signs in some cats.

All pets with diabetes mellitus benefit from being fed a well-balanced diet, most often a diet high in protein and low in carbohydrates. A low carbohydrate diet decreases the amount of glucose absorbed from the intestinal tract and lowers the requirement for insulin.

If there are no predisposing causes, or if correction of the predisposing causes does not lead to resolution of the diabetes, specific treatment is required. Although a small proportion of cats will respond to oral hypoglycemic medication, most cats and all dogs will require daily insulin injections.  Even though some cats do respond to oral hypoglycemic medications, many owners actually find it easier to give daily injections to cats rather than daily pills.

During the initial stages of treatment, pets usually require several hospital visits until an appropriate insulin dosage is determined.  Our goal is to achieve initial stabilization within a few days to a few weeks, but in certain cases, this initial stabilization can prove challenging.  Very small needles are available which cause no pain to the pet, and within a short time the procedure becomes routine for everyone involved.  With careful monitoring and appropriate life style adjustments, our dog and cat diabetic patients frequently lead long and happy lives.

Thyroid disease is another very common problem we encounter at Fountain City Animal Hospital.  In cats, the problem is usually hyperthyroidism, or over-activity of the thyroid gland, and in dogs, we most commonly see hypothyroidism, or under activity of the thyroid gland.

Hyperthyroidism in cats is a disorder resulting from excessive thyroid hormone. The disease occurs in middle to older cats without sex or breed predilection. Though functional benign enlargement (adenoma) is most common (98%), thyroid carcinoma (cancer) is another cause (2%). About 70% of cats have both lobes of the thyroid gland affected.  Symptoms of hyperthyroidism can be variable, including some or all of the following: poor hair coat, rapid heart rate, voracious appetite or thirst, anxiety or nervousness, intermittent soft stools or vomiting, and vocalizing.  Hyperthyroid cats always lose weight. 

The diagnosis of hyperthyroidism is usually fairly straightforward when we find an elevation of circulating thyroid hormone on blood tests. We will often also be able to palpate an abnormally enlarged thyroid gland in your cat’s neck.  The most commonly chosen option for treatment is daily anti-thyroid medication, but there are other options.  Surgical removal of the thyroid gland can be done, but is rarely chosen any more.  Radioactive iodine therapy is an option that some choose, since it can be performed locally at the U.T. College of Veterinary Medicine and requires no follow-up at home care once it is done.  The most recent addition to treatment options is a change to a special diet that is virtually iodine deficient and thereby starves the thyroid gland while being nutritionally complete in every other way.  If your cat is diagnosed with hyperthyroidism, we would discuss all the pros and cons of each option.   Cats generally do very well if treated appropriately and go on to live long and happy lives. 

Hypothyroidism in dogs is a disorder resulting from insufficient thyroid hormone, in response to inflammation or shrinkage of the thyroid gland.  Hypothyroidism occurs more commonly in medium to large breed dogs and usually in middle aged dogs.  The most common signs of low thyroid function in dogs include some or all of the following: loss or thinning of the fur, dull hair coat, excess shedding or scaling, weight gain, reduced activity and reduced ability to tolerate the cold. The hair loss occurs primarily over the body, sparing the head and legs, and is usually not accompanied by itching or redness of the skin, unless a secondary infection is present. Some dogs will have thickening of the skin and increased skin pigment, especially in areas of friction, such as the armpit (axilla). Hypothyroid dogs often have ear infections and show ear pain, redness, and odor.  The accumulation of substances called mucopolysaccharides can cause the muscles of the face to droop giving the dog a facial expression that is sometimes called “tragic.”  Less commonly seen in dogs with hypothyroidism include dilation of the esophagus (megaesophagus) causing regurgitation, and abnormal function of nerves or muscles leading to weakness or abnormal ability to walk.  Routine blood tests can be affected by hypothyroidism, although the changes are not consistent and can be subtle. Dogs may have a mild anemia and increased levels of cholesterol. There are several blood tests that can be used to confirm a suspected diagnosis of hypothyroidism. Blood testing for hypothyroidism is usually performed as a panel of several tests in order to increase the yield of these tests. The results of some of these tests can be influenced by the presence of other non-thyroid diseases, so test results must be considered in light of the whole picture.  Treatment of hypothyroidism is by giving oral replacement hormone for the rest of the dog’s life.  It usually takes 4 to 6 weeks before regrowth of the fur is apparent.  Blood levels of the T4 are often measured in order to fine tune the dose.

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